Optical image stabilization actuator driver power distribution control

ABSTRACT

Various embodiments provide an optical image stabilization circuit including a drive circuit having a power waveform generator and a power waveform conversion circuit. The power waveform generator generates a power waveform. The power waveform conversion circuit converts the power waveform to a power drive signal. An actuator is then driven by the power drive signal to move a lens accordingly and compensate for any movements and vibrations of a housing of the lens.

BACKGROUND

Technical Field

The present disclosure is directed to generating power drive signals foran actuator.

Description of the Related Art

Digital cameras have progressed to smaller sizes, lower weight, andhigher resolutions. A drawback to this development, however, has beenthe impact of minor movements on image quality. Particularly, subtlemovements or vibrations while capturing an image often causes imageblurring. This is especially a problem for smartphones with built-incameras, where users capture images with outstretched arms and have agreater chance of involuntary movements. Image stabilization is widelyused to minimize image blurring. Current methods of image stabilizationinclude digital image stabilization, electronics image stabilization,and optical image stabilization. Generally, digital image stabilizationand electronics image stabilization require large amounts of memory andprocessor resources. Optical image stabilization, on the other hand,minimizes memory and processor demands by adjusting the lens positionitself. As such, optical image stabilization is ideal for portabledevices, such as smartphones and tablets with built-in cameras.

In general, optical image stabilization minimizes image blurring bysensing movements of a housing and compensating for the movements byadjusting the position of the camera lens. For example, see “OpticalImage Stabilization (OIS),” Rosa et al, STMicroelectronics. Opticalimage stabilization circuits typically include a gyroscope, acontroller, and a drive circuit that includes a large current source todrive an actuator to move the camera lens.

Most drive circuits output either a linear power drive signal having aconstant voltage level or a standard pulse-width modulation power drivesignal having high (i.e., 1) and low (i.e., 0) voltage levels with acertain duty cycle or frequency. For example, see “Optical ImageStabilization (OIS),” Rosa et al, STMicroelectronics. Linear power drivesignals and pulse-width modulation power drive signals each having theirown advantages. Namely, linear power drive signals are used to reducenoise, and standard pulse-width modulation power drive signals are usedfor power efficiency. Drive circuits, however, generally do not generateboth linear and standard pulse-width modulation power drive signals.

BRIEF SUMMARY

The present disclosure provides an optical image stabilization circuitthat generates power drive signals to drive an actuator.

According to one embodiment, a housing includes a camera lens; anactuator to move the lens; a position sensor; and an optical imagestabilization circuit having a gyroscope, a controller, and a drivecircuit. A power waveform generator of the drive circuit generates apower waveform based on power drive signal data received from themicrocontroller. Subsequently, a power waveform conversion circuit ofthe drive circuit converts the power waveform to a corresponding powerdrive signal. The actuator is then driven with the power driven signalto move the lens accordingly and compensate for any movements andvibrations of the housing.

The optical image stabilization circuit disclosed herein is capable ofgenerating linear power drive signals, standard pulse-width modulationpower drive signals, and multi-state pulse-width modulation power drivesignals to drive the actuator. The frequency of the power drive signalsare limited only by the speed of the power waveform generator and thepower waveform conversion circuit of the drive circuit.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing and other features and advantages of the presentdisclosure will be more readily appreciated as the same become betterunderstood from the following detailed description when taken inconjunction with the accompanying drawings.

FIG. 1A is a block diagram illustrating an example of a housingincluding an optical image stabilization circuit according to oneembodiment as disclosed herein.

FIG. 1B is a circuit diagram illustrating an example of a power waveformconversion circuit of a drive circuit according to one embodiment asdisclosed herein.

FIG. 1C is an example of a camera undergoing movement and correctionaccording to embodiments disclosed herein.

FIG. 2 is a flow diagram illustrating an example of a process for anoptical image stabilization circuit according to one embodiment asdisclosed herein.

FIG. 3 is a flow diagram illustrating an example of a process forgenerating a power waveform according to one embodiment as disclosedherein.

FIG. 4A is a first example of a fixed order power waveform according toembodiments disclosed herein.

FIG. 4B is an example of a sorted order power waveform based on thefixed order power waveform of FIG. 4A according to embodiments disclosedherein.

FIG. 4C is an example of a multi cycle sorted order power waveform basedon the fixed order power waveform of FIG. 4A according to embodimentsdisclosed herein.

FIG. 5A is a second example of a fixed order power waveform according toembodiments disclosed herein.

FIG. 5B is a second example of a sorted order power waveform based onthe fixed order power waveform of FIG. 5B according to embodimentsdisclosed herein.

FIG. 6A, FIG. 6B, FIG. 6C, and FIG. 6D are examples of fixed order powerwaveforms having a range of transition limit values according toembodiments disclosed herein.

FIG. 7A, FIG. 7B, FIG. 7C, and FIG. 7D are examples of fixed order powerwaveforms having a range of amplitude bit resolution values according toembodiments disclosed herein.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various embodiments of thedisclosure. However, one skilled in the art will understand that thedisclosure may be practiced without these specific details. In someinstances, well-known details associated with optical imagestabilization have not been described to avoid obscuring thedescriptions of the embodiments of the present disclosure.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment. Thus, the appearances of the phrases “in one embodiment” or“in an embodiment” in various places throughout this specification arenot necessarily all referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics may be combined inany suitable manner in one or more embodiments.

In the drawings, identical reference numbers identify similar featuresor elements. The size and relative positions of features in the drawingsare not necessarily drawn to scale.

FIG. 1A is a block diagram illustrating an example of a housing 10according to principles disclosed herein. A camera lens 12, an actuator14, a position sensor 16, and an optical image stabilization circuit 18are positioned within the housing 10. The optical image stabilizationcircuit 18 includes a gyroscope 20, a microcontroller 22, and a drivecircuit 24. The drive circuit 24 includes a power waveform generator anda power waveform conversion circuit 28.

The housing 10 may be any device that includes a camera. For example,the housing 10 may be a smartphone, a tablet, a digital camera, or aportable computer with a built-in camera.

The actuator 14 is coupled to the lens 12 and the drive circuit 24. Theactuator 14 is configured to move the lens 12 in response to a powerdrive signal from the drive circuit 26. The actuator 14 may be basedupon a variety of different technologies, such as adaptive liquidlenses, shape memory alloys, or piezo-electric motors. In a preferredembodiment, the actuator 14 is based on a voice coil motor.

The position sensor 16 is coupled to the lens 12 and the drive circuit24. The position sensor 16 is configured to measure a position of thelens 12, and provide position data of the position of the lens 12 to thedrive circuit 24. The position sensor 16 may be any type of sensorconfigured to detect movements of the lens 12. For example, the positionsensor 16 may include photo sensors or hall sensors.

The optical image stabilization circuit 18 is coupled to the actuator 14and the position sensor 16. The optical image stabilization circuit 18performs an image stabilization process to minimize the impact ofmovements or vibrations inflicted upon the housing 10. As previouslystated, the optical image stabilization circuit 18 includes thegyroscope 20, the microcontroller 22, and the drive circuit 24.

The gyroscope 20 is coupled to the microcontroller 22. The gyroscope 20is configured to detect movements of the housing 10 during the instantthat a photograph is being taken. For example, if the housing 10 is asmartphone having the lens 12, the gyroscope 20 detects the movements ofthe smartphone when the aperture of the camera opens to record the imageafter the user presses the button to take a picture. The gyroscope 20will sense then output any movement, such as angular rates alonglateral, vertical, and longitudinal axes, of the housing 10 having thecamera and lens 12 therein. The movement data of the housing 10 isprovided to the microcontroller 22 to be used as a reference of angulardisplacement of the housing 10 relative to the lens 12. Any movement ofthe housing that occurs for the brief time period that the image isactually being recorded as digital data is counteracted by an equal andopposite movement of the lens itself.

The microcontroller 22 is coupled to the gyroscope 20 and the drivecircuit 24. The microcontroller 22 is configured to perform a lensmovement control cycle operation to provide image stabilization while apicture is being taken. Particularly, the microcontroller 22 receivesmovement data of the movement of the housing 10 from the gyroscope 20and position data of the position of the lens 12 from the positionsensor 16 via the drive circuit 24. The microcontroller 22 thencalculates power drive signal data based on the movement data and theposition data. The power drive signal data is used to generate powerdrive signals to move the lens to offset and compensate for anymovements and vibrations of the housing 10. In one embodiment, as willbe discussed in further detail with respect to FIG. 3, the power drivesignal data includes a power input parameter ISP, a total bit resolutionRES, an amplitude bit resolution AMP, and a transition limit TRN. Themicrocontroller 22 provides the power drive signal data to the drivecircuit 24. The drive circuit 24 then provides a power drive signalbased on the power drive signal data to the actuator 14 to move oradjust the lens 12 accordingly.

The drive circuit 24 is coupled to the actuator 14, the position sensor16, and the microcontroller 22. As previously discussed, the drivecircuit 24 is configured to receive position data of the position of thelens 12 from the position sensor 16, and receive power drive signal datafrom the microcontroller 22. The drive circuit 24 is also configured toprovide power drive signals to the actuator 14 to move the lens 12. Aspreviously stated, the drive circuit 24 includes the power waveformgenerator 26 and the power waveform conversion circuit 28.

The power waveform generator 26 generates a power waveform based on thepower drive signal data from the microcontroller 22. As will bediscussed in further detail with respect to FIG. 3, a power waveformconsists of a plurality of time intervals with each time interval havingan amplitude value based on the power drive signal data from themicrocontroller 22. The power waveform may have a linear shape, astandard pulse-with modulation shape, or a multi-state pulse-widthmodulation shape that can have any number of different power levels,duty cycles, and frequencies. The power waveform generator 26 providesthe power waveform to the power waveform conversion circuit 28. Thepower waveform generator 26 will be discussed in further detail withrespect to FIG. 3.

The power waveform conversion circuit 28 converts the power waveformreceived from the power waveform generator 26 to a corresponding powerdrive signal that is capable of driving the actuator 14. The powerwaveform conversion circuit 28 is capable of converting a power waveformhaving any shape, such as a linear shape, a standard pulse-withmodulation shape, or a multi-state pulse-width modulation shape. Thepower waveform conversion circuit 28 will be discussed in further detailwith respect to FIG. 1B.

It should be noted that although only one drive circuit, actuator, andposition sensor are shown in FIG. 1A, the housing 10 may include anynumber of drive circuits, actuators, and position sensors.

FIG. 1B is a circuit diagram illustrating an example of the powerwaveform conversion circuit 28 of the drive circuit 24 according to oneembodiment. In the embodiment shown in FIG. 1B, the actuator 14 is avoice coil motor having a voice coil 38. The power waveform conversioncircuit 28 of FIG. 1B includes a digital to analog converter 30; anoperational amplifier 32; various integrated circuit components 34,including transistors, resistors, and capacitors; and an H bridgecircuit 36. The digital to analog converter 30, the operationalamplifier 32, the integrated circuit components 34, and the H bridgecircuit 36 are coupled to each other as shown in FIG. 1B.

The digital to analog converter 30 is configured to receive the powerwaveform from the power waveform generator 26 and convert the powerwaveform to an equivalent voltage signal having the same shape as thepower waveform. Particularly, the digital to analog converter 30converts the amplitude value for each time interval of the powerwaveform to a corresponding voltage level. In one embodiment, thedigital to analog converter 30 dynamically adjusts the voltage signal tominimize any system offset error. That is, the digital to analogconverter 30 tunes the voltage signal by increasing or decreasing itsvoltage levels to provide an absolute zero crossing.

The operational amplifier 32 and the integrated circuit components 34are configured to convert the voltage signal generated by the digital toanalog converter 30 to a power drive signal to drive the voice coil 38.Particularly, the voltage signal is converted to an equivalent electriccurrent signal. In one embodiment, the operational amplifier 32 and theintegrated circuit components 34 applies a gain to the voltage signalsuch that resulting electric current signal is at a required electriccurrent level to drive the H bridge circuit 36 and the voice coil 38.For example, the operational amplifier 32 and the integrated circuitcomponents 32 may convert the voltage signal to an electric currentsignal having amplitudes between 0 milliamps to 120 milliamps. Theentire available range of voltage or current can be divided into units,with each unit being the sized needed to cover the available range. Forexample, if the max amplitude is 7 units, then a 3 bit number can beused. The 120 milliamps is divided into 7 equals units of about 17milliamps each, with a value of zero units being zero milliamps.Similarly, if a more fine power division is desired, such as 9 or 12,then each unit will equal about 13.3 or 10 milliamps, respectively.Further, if a different maximum value is provided, such as 70 milliampsor 240 milliamps, then the available maximum will be divided into thedesired number of discrete steps based on the number of units available,whether 8, 9, 10, 16, 24 or the like. For example, use of 32 differentunits, with zero being one unit is preferred embodiment. The terms todescribe motor drive power can be defined in terms of volts, current orcombinations thereof, as is known in the art. H bridges and voice coilsare known in the art and will not be discussed in detail herein.

It should be understood that the power waveform conversion circuit 28may be used in conjunction with any type of actuator. As previouslydiscussed, the actuator 14 may be may be based upon a variety ofdifferent technologies, such as voice coil motors, adaptive liquidlenses, shape memory alloys, or piezo-electric motors. In anotherembodiment, the voice coil 38 is replaced with a shape memory alloy andthe H bridge circuit is modified accordingly to drive the shape memoryalloy as is known in the art.

FIG. 1C illustrates one physical embodiment of use of the circuit andcompensation as disclosed herein. As shown in FIG. 1C, the lens 12 iswithin a smartphone housing 10. Most smartphones today havesophisticated cameras. In addition, most smartphones today includegyroscopes, accelerometers, and various other sensors to sense movementof the smartphone. Within the housing 10 of the smartphone are containedall of the elements as shown in FIG. 1A, namely, the gyroscope 20, themicrocontroller 22, the drive circuit 24, the lens 12 together with theactuator 14 and the position sensor 16. These components are not shownin FIG. 1C because they are inside the housing 10. The camera is pointedat a scene 40, which the user is taking a picture of by pressing onbutton 42. When the user's finger presses button 42 to take a picture,the housing 10 moves with a slight wiggle, as indicated by movementlines 44. This causes the camera, as well as the lens, to move. Undernormal conditions, the movement of the housing 10, which contains thecamera and the lens 12, occurs simultaneously with taking a picture andwill cause the picture to be blurry. However, the picture of scene 40shows up clear on display 46 because it contains the structure shown inFIG. 1A. Namely, when the camera moves while the user is pressing thebutton 42, the gyroscope 20 senses the movement and a power drive signalis sent, via the drive circuit 22, to the actuator 14 to move the lens12 opposite to the movement of the housing 10. Since the movement of thelens 12 counteracts the movement of the housing 10, the picture as shownon the display 46 is clear. The operation of the optical imagestabilization circuit 18, the actuator 14, the position sensor 16, andthe lens 12, as further explained elsewhere herein, allows a clear imageof scene 40 to be taken, even though the camera is moving, as shown bythe movement lines 44, at the exact instant the camera is taking apicture.

FIG. 2 is a flow diagram illustrating an example of a process 48 for theoptical image stabilization circuit 18 according to principles disclosedherein.

At a first step 50, the microcontroller 22 receives movement data of themovement of the housing 10 from the gyroscope 20 and position data ofthe position of the lens 12 from the position sensor 16 via the drivecircuit 24.

In a subsequent step 52, the microcontroller 22 calculates power drivesignal data based on the movement data and the position data. The powerdrive signal data is used by the drive circuit 24 to generate powerdrive signals to compensate for any movements and vibrations of thehousing 10. In one embodiment, as will be discussed in further detailwith respect to FIG. 3, the power drive signal data includes a powerinput parameter ISP, a total bit resolution RES, an amplitude bitresolution AMP, and a transition limit TRN.

In step 54, the power waveform generator 26 of the drive circuit 24receives the power drive signal data generates a power waveform based onthe power drive signal data. The generation of the power waveform willbe discussed in further detail with respect to FIG. 3.

In step 56, the power waveform conversion circuit 28 converts the powerwaveform from the power waveform generator 26 to a corresponding powerdrive signal. In particular, as previously discussed, the digital toanalog converter 30 receives the power waveform from the power waveformgenerator 26 and converts the power waveform to an equivalent voltagesignal having the same shape. The operational amplifier 32 and theintegrated circuit components 34 then converts the voltage signal to apower drive signal to drive the H bridge circuit 34 and the voice coil36.

In step 58, the actuator 14 is driven by the power drive signal to movethe lens 12 accordingly and compensate for any movements and vibrationsof the housing 10.

FIG. 3 is a flow diagram illustrating an example of a process 60 for thegenerating of the power waveform in step 54 of process 48 according toprinciples disclosed herein. It is beneficial to review FIG. 3,particularly step 88, simultaneously with FIG. 4A. FIG. 4A is an exampleof a fixed order power waveform.

At step 62, the power wave form generator 26 of the drive circuit 24receives the power drive signal data from the microcontroller 22. In oneembodiment, the power drive signal data includes a power input parameterISP, a total bit resolution RES, an amplitude bit resolution AMP, and atransition limit TRN. In another embodiment, the total bit resolutionRES, the amplitude resolution AMP, and the transition limit TRN is notincluded in the power drive signal data, and is instead preprogrammed into the power waveform generator 26. Values for the power input parameterISP, the total bit resolution RES, the amplitude bit resolution AMP, andthe transition limit TRN that are used to calculate the fixed orderpower waveform shown in FIG. 4A is summarized in Table A. Table A alsoincludes a timing resolution PUL for the fixed order power waveform ofFIG. 4A, which will be described in further with respect to step 64.

TABLE A Power input parameter ISP 26 Total bit resolution RES 5Amplitude bit resolution AMP 3 Transition limit TRN 2 Timing bitresolution PUL 2

The power input parameter ISP is used to generate a power waveform. Thepower input parameter ISP specifies the total power of the powerwaveform. The power input parameter ISP is composed of a base amplitudebit range BAR that specifies a base amplitude value BAV, a timing bitrange TRG that specifies a timing value TVL, and an incrementalamplitude bit range IAR that specifies an incremental amplitude valueIAV. For example, the fixed order power waveform of FIG. 4A has a powerinput parameter ISP equal to a bit value of 011010 or a decimal value of26. The base amplitude bit range BAR, the timing bit range TRG, and theincremental amplitude bit range IAR and their corresponding values willbe discussed in further detail with respect to steps 66, 74, and 82,respectively.

The total bit resolution RES is the bit resolution of the power inputparameter ISP. The total bit resolution RES determines the largest valuethat the power input parameter ISP may be. For example, the fixed orderpower waveform of FIG. 4A has a total bit resolution RES of 5 bits. As aresult, the power input parameter ISP of the fixed order power waveformof FIG. 4A must be less than or equal to 2⁵ or 32. The total bitresolution RES may have any value that the hardware of the opticalstabilization circuit 18 will allow for (12 bits, 24 bits, etc.).

The amplitude bit resolution AMP is the bit resolution for theamplitudes of a power waveform. Namely, the amplitude bit resolution AMPdetermines the number of amplitude units over which the amplitude canvary. For example, the fixed order power waveform of FIG. 4A has anamplitude bit resolution AMP of 3 bits. Thus, the fixed order powerwaveform of FIG. 4A may have amplitude values between 0 and 2³, or 8,amplitude units. An amplitude unit is an amplitude increment that isused by the digital to analog converter 30 to convert a power waveformto an equivalent voltage signal. One amplitude unit, for instance, mayconverted by the digital to analog converter 30 to one microvolt,millivolt, or one volt. The amplitude bit resolution AMP should be lessthan or equal to the total bit resolution RES.

The transition limit TRN limits a power waveform's amplitude transitionbetween consecutive time intervals. That is, the transition limit TRN isthe maximum amount of amplitude units that a power waveform may changefrom one time interval to a subsequent time interval. For example, thefixed order power waveform of FIG. 4A has a transition limit TRN of 2bits. Thus, the maximum change between consecutive intervals of thefixed order power waveform of FIG. 4A is 2² or 4 amplitude units. Thetransition limit TRN should be less than or equal to the amplitude bitresolution AMP.

In step 64, the total bit resolution RES and the amplitude bitresolution AMP is used to calculate a timing bit resolution PUL. Thetiming bit resolution PUL is the total amount of bits that is used tospecify a timing value TVL. The total bit resolution RES is calculatedusing the following equation:PUL=RES−AMPFor example, the fixed order power waveform of FIG. 4A has a timing bitresolution PUL of 2 bits. The timing value TVL will be described infurther detail with respect to step 76.

The power input parameter ISP, the total bit resolution RES, theamplitude bit resolution AMP, the transition limit TRN, and the timingbit resolution PUL are used to calculate a base amplitude bit range BAR,a timing bit range TRG, an incremental amplitude bit range IAR, a baseamplitude value BAV, a timing value TVL, an incremental amplitude valueIAV, a minimum amplitude output value MIN, a maximum amplitude outputvalue MAX, an incremental amplitude output value INC, a maximumamplitude output value length TUH, and a minimum amplitude output valuelength TUL. The calculations of these values for the fixed order powerwaveform shown in FIG. 4A is summarized in Table B. It is important notethat an additional bit is added when performing the calculations in casethe power input parameter ISP is equal to its maximum value. Forexample, 6 bits are used for the calculations shown in Table B toaccount for the maximum bit value of 100000 of the power input parameterISP, which has a total bit resolution RES of 2⁵ or 32.

TABLE B Binary value Bit position 5 4 3 2 1 0 Decimal value Baseamplitude bit range 1 1 0 0 0 0 48 BAR Timing bit range TRG 0 0 1 1 0 012 Incremental amplitude bit 0 0 0 0 1 1 3 range IAR Power inputparameter ISP 0 1 1 0 1 0 26 Base amplitude value BAV 0 1 0 0 0 0 16Timing value TVL 0 0 1 0 0 0 8 Incremental amplitude 0 0 0 0 1 0 2 valueIAV Minimum amplitude 0 0 0 1 0 0 4 output value MIN Maximum amplitude 00 1 0 0 0 8 output value MAX Incremental amplitude 0 0 0 1 1 0 6 outputvalue INC Maximum amplitude 0 0 0 0 1 0 2 output value length TUHMinimum amplitude 0 0 0 0 0 1 1 output value length TUL

In step 66, the base amplitude bit range BAR is calculated. The baseamplitude bit range BAR is the bit range of the power input parameterISP that specifies the base amplitude value BAV. Particularly, the baseamplitude bit range BAR is used as a mask to parse the base amplitudevalue BAV from the power input parameter ISP. The base amplitude bitrange BAR is calculated using the following equation:BAR=2^(RES+1)−2^(TRN+PUL)For example, referring to Table B, the fixed order power waveform ofFIG. 4A has a base amplitude bit range BAR equal to a bit value of110000. Thus, bit positions 4 and 5 of the power input parameter ISPspecifies the base amplitude value BAV for the fixed order powerwaveform of FIG. 4A.

In step 68, the base amplitude value BAV is calculated. The baseamplitude value BAV is an intermediary value that is used to calculatethe minimum amplitude output value MIN. The base amplitude value BAV isobtained by parsing the power input parameter ISP by using the baseamplitude bit range BAR. Particularly, the base amplitude value BAV iscalculated using the following equation:BAV=ISP AND BARFor example, referring to Table B, the fixed order power waveform ofFIG. 4A has a base amplitude value BAV equal to a bit value of 010000.

In step 70, the minimum amplitude output value MIN is calculated. Theminimum amplitude output value MIN is the lowest amplitude that a powerwave form may have. The minimum amplitude output value MIN is calculatedby removing the bits of the timing bit range TRG. This is done byshifting the base amplitude value BAV to the right by a number of bitsequal to the timing bit resolution PUL. For instance, referring to TableB, the fixed order power waveform of FIG. 4A has a minimum amplitudeoutput value MIN equal to a bit value of 000100 or a decimal value of 4.This is obtained by shifting the base amplitude value BAV, which has abit value of 010000, to the right by the number of bits equal to thetiming bit resolution PUL, which is 2 bits. Thus, the lowest amplitudethat the fixed order power waveform may have is 4 amplitude units.

In step 72, the maximum amplitude output value MAX is calculated. Themaximum amplitude output value MAX is the largest amplitude that a powerwaveform may have. The maximum amplitude output value MAX is calculatedusing the following equation:MAX=MIN+2^(TRN)For example, referring to Table B, the fixed order power waveform ofFIG. 4A has a maximum amplitude output value MAX equal to a bit value of001000 or a decimal value of 8. As such, the largest amplitude that thefixed order power waveform of FIG. 4A may have is 8 amplitude units, themaximum amplitude available in this example.

In step 74, the timing bit range TRG is calculated. The timing bit rangeTRG is the bit range of the power input parameter ISP that specifies thetiming value TVL. Particularly, the timing bit range TRG is used as amask to parse the timing value TVL from the power input parameter ISP.The timing bit range TRG is calculated using the following equation:TRG=2^(TRN)*(2^(PUL)−1)For instance, referring to Table B, the fixed order power waveform ofFIG. 4A has a timing bit range TRG equal to a bit value of 001100. Assuch, bit positions 2 and 3 of the power input parameter ISP specifiesthe timing value TVL for the fixed order power waveform of FIG. 4A.

In step 76, the timing value TVL is calculated. The timing value TVL isan intermediary value that is used to calculate the maximum amplitudeoutput value length TUH. The timing value TVL is obtained by parsing thepower input parameter ISP by using the timing bit range TRG.Particularly, the timing value TVL is calculated using the followingequation:TVL=ISP AND TRGFor example, referring to Table B, the fixed order power waveform ofFIG. 4A has a timing value TVL equal to a bit value of 001000.

In step 78, the maximum amplitude output value length TUH is calculated.The maximum amplitude output value length TUH is the total number oftime units of the maximum amplitude output value MAX that a powerwaveform may have. Each time unit represents an increment of time. Onetime unit, for instance, may be equal to one nanosecond, onemicrosecond, or one second. The maximum amplitude output value lengthTUH is calculated by shifting the timing value TVL to the right by anumber of bits equal to the transition limit TRN. For instance,referring to Table B, the fixed order power waveform of FIG. 4A has amaximum amplitude output value length TUH equal to a bit value of 000010or a decimal value of 2. This is obtained by shifting the timing valueTVL, which has a bit value of 001000, to the right by the number of bitsequal to the transition limit TRN, which is 2 bits. Thus, the fixedorder power waveform of FIG. 4A has the maximum amplitude output valueMAX, which in this case is 8 amplitude units, for a total of 2 timeunits.

In step 80, the minimum amplitude output value length TUL is calculated.The minimum amplitude output value length TUL is the total number oftime units of the minimum amplitude output value MIN that a powerwaveform may have. The minimum amplitude output value length TUL, whichis the complement of the maximum amplitude output value length TUH, iscalculated using the following equation:TUL=2^(PUL)−1−TUHFor example, referring to Table B, the fixed order power waveform ofFIG. 4A has a minimum amplitude output value length TUL equal to a bitvalue of 000001 or a decimal value of 1. Thus, the fixed order powerwaveform of FIG. 4A has the minimum amplitude output value MIN, which inthis case is 4 amplitude units, for a total of 1 time unit.

In step 82, the incremental amplitude bit range IAR is calculated. Theincremental amplitude bit range IAR is the bit range of the power inputparameter ISP that specifies the incremental amplitude value IAV.Namely, the incremental amplitude bit range IAR is used as a mask toparse the incremental amplitude value IAV from the power input parameterISP. The incremental amplitude bit range IAR is calculated using thefollowing equation:IAR=2^(TRN)−1For example, referring to Table B, the fixed order power waveform ofFIG. 4A has an incremental amplitude bit range IAR equal to a bit valueof 000011. As a result, bit positions 0 and 1 of the power inputparameter ISP specifies the incremental amplitude value IAV.

In step 84, the incremental amplitude value IAV is calculated. Theincremental amplitude value IAV is an intermediary value that is used tocalculate the incremental amplitude output value INC. The incrementalamplitude value IAV is obtained by parsing the power input parameter ISPby using the incremental amplitude bit range IAR. Particularly, theincremental amplitude value IAV is calculated using the followingequation:IAV=ISP AND IARFor example, referring to Table B, the fixed order power waveform ofFIG. 4A has an incremental amplitude value IAV, which equal to a bitvalue of 000010.

In step 86, the incremental amplitude output value INC is calculated.The incremental amplitude output value INC is an intermediary amplitudeof a power waveform that is between the minimum amplitude output valueMIN and the maximum amplitude output value MAX. The incrementalamplitude output value INC is calculated using the following equation:INC=MIN+IAVFor instance, referring to Table B, the fixed order power waveform ofFIG. 4A has an incremental amplitude output value INC equal to a bitvalue of 000110 or a decimal value of 6. As such, the incrementalamplitude output value INC of the fixed order power waveform of FIG. 4Ais 6 amplitude units. It should be noted that although step 70 and step86 are shown to be in parallel with each other in FIG. 3, step 86 isperformed subsequent to step 70 because the incremental amplitude outputvalue INC uses the minimum amplitude output value MIN in itscalculation.

In step 88, the power waveform is generated. The power wave form isformed by using the minimum amplitude output value MIN, the maximumamplitude output value MAX, the incremental amplitude output value INC,the maximum amplitude output value length TUH, and the minimum amplitudeoutput value length TUL.

The total number of time units of the power waveform is calculated usingthe following equation:Total number of time units=2^(PUL)The total number of time units represents the length of the powerwaveform. For example, the fixed order power waveform of FIG. 4A has atotal length of 4 time units.

In one embodiment, the power waveform is a fixed order power waveform. Afixed order power waveform is composed of a plurality of time intervals.Time intervals for the fixed order power waveform shown in FIG. 4A aresummarized in Table C.

TABLE C Time interval Amplitude Length of time interval 0 6 1 1 4 1 2 82The first time interval, or time interval 0, of a fixed order powerwaveform has a length of 1 time unit. For instance, referring to TableC, time interval 0 for the fixed order power waveform of FIG. 4A has alength of 1 time unit. The lengths of subsequent time intervals aredetermined by performing a bit progression. That is, the second timeinterval has a length equal to 2° time units, the third time intervalhas a length equal to 2¹ time units, the fourth time interval has alength equal to 2² time units, and so on. As a result, each successivetime interval has a length equal to double the length of the previoustime interval. For example, referring to Table C, time interval 1 forthe fixed order power waveform of FIG. 4A has a length of 1 time unitand time interval 2 has a length of 2 time units.

For a fixed order power waveform, the amplitude of each time interval isequal to the minimum amplitude output value MIN, the maximum amplitudeoutput value MAX, or the incremental amplitude output value INC. Theamplitude of the first time interval, time interval 0, is equal to theincremental amplitude output value INC. Namely, the amplitude of timeinterval 0 is calculated using the following equation:Time interval 0=INCFor example, referring to Tables B and C, time interval 0 for the fixedorder power waveform of FIG. 4A has an amplitude equal to theincremental amplitude output value INC, which is 6. The amplitudes ofthe remaining time intervals are equal to the minimum amplitude outputvalue MIN or the maximum amplitude output value MAX based on the maximumamplitude output value length TUH. Specifically, the amplitude of thesecond time interval, time interval 1, is calculated using the followingequation:If the least significant bit of TUH is 1, then timing interval 1=MAX,else timing interval 1=MINFor example, referring to Tables B and C, time interval 1 for the fixedorder power waveform of FIG. 4A has an amplitude equal the minimumamplitude output value MIN, which is 4, because the least significantbit of the maximum amplitude output value TUH is equal to 0. Eachsuccessive time interval is calculated using the correspondingsuccessive bit of the maximum amplitude output value length TUH. Forexample, the amplitude of time interval 2 is calculated using thefollowing equation:If the second from the least significant bit of TUH is 1, then timinginterval 2=MAX, else timing interval 2=MINFor example, referring to Tables B and C, time interval 2 for the fixedorder power waveform of FIG. 4A has an amplitude equal the maximumamplitude output value MAX, which is 8, because the second from theleast significant bit of the maximum amplitude output value TUH is equalto 1.

In another embodiment, the power waveform is a sorted order powerwaveform. FIG. 4B is an example of a sorted order power waveform basedon the fixed order power waveform shown in FIG. 4A. In contrast to afixed order power waveform, a sorted order power waveform order may havetime intervals arranged in any order. In a preferred embodiment, timeintervals are ordered to minimize the amount of transitions between themaximum amplitude output value MAX and the minimum amplitude outputvalue MIN to prevent unnecessary transients in the system. For instance,time intervals that have amplitudes equal to the maximum amplitudeoutput value MAX may be grouped together to be consecutive and timeintervals that have amplitudes equal to the minimum amplitude outputvalue MIN may be grouped together to be consecutive. In one embodiment,a sorted order power waveform is formed by having the incrementalamplitude output value INC for 1 time unit, the maximum amplitude outputvalue MAX for a number of time units equal to the maximum amplitudeoutput value length TUH, and the minimum amplitude output value MIN fora number of time units equal to the minimum amplitude output valuelength TUL. For example, referring to Table B, the sorted order powerwaveform of FIG. 4B has an amplitude equal to 6 amplitude units (i.e.,the incremental amplitude output value INC) for 1 time unit, 8 amplitudeunits (i.e., the maximum amplitude output value MAX) for 2 time units(i.e., the maximum amplitude output value length TUH), and 4 amplitudeunits (i.e., the minimum amplitude output value MIN) for 1 time unit(i.e., the minimum amplitude output value length TUL). As an additionalexample, FIG. 5A shows an example of a fixed order power waveform havinga power input parameter ISP equal to 11, a total bit resolution RESequal to 5, an amplitude bit resolution AMP equal to 1, a transitionlimit TRN equal to 1, and a timing bit resolution PUL equal to 4. FIG.5B shows an example of a sorted power waveform based on the fixed orderpower waveform shown in FIG. 5A. As shown in FIG. 5B, the amount oftransitions between the maximum amplitude output value MAX and theminimum amplitude output value MIN is minimized.

In a further embodiment, the power waveform is a multi-cycle powerwaveform. FIG. 4C is an example of a multi cycle sorted order powerwaveform. For a multi-cycle power waveform, a fixed order power waveformor a sorted order power waveform is repeated for successive cycles. Forexample, as shown in FIG. 4C, the sorted order power wave of FIG. 4B isrepeated for 4 cycles.

The power waveform generator 26 as described herein is capable ofgenerating a scalable power waveform that may have any power level, dutycycle, and frequency that the hardware of the system allows for byvarying the power input parameter ISP, the total bit resolution RES, theamplitude bit resolution AMP, or the transition limit TRN. The powerwaveform may have a linear shape and a standard pulse-width modulationshape. For example, a power waveform having linear shape may be createdby setting the total bit resolution RES to be equal to the amplitude bitresolution AMP, and a power waveform having a standard pulse-widthmodulation shape may be created by setting the amplitude bit resolutionAMP to be equal to zero. In addition, the power waveform generator 26 iscapable of generating a multi-state pulse-width modulation powerwaveform that can have multiple different power levels, duty cycles, andfrequencies. In contrast to a standard pulse-width modulation powerwaveform, in which there are only two power levels (high and low), amulti-state pulse-width modulation power waveform may have power levelsof 1, ½, ⅓, ¼, or some other value less than the full power level andgreater than the lowest power level, and the width of each pulse withina cycle can vary greatly.

FIG. 6A, FIG. 6B, FIG. 6C, and FIG. 6D illustrates how a fixed orderpower waveform will vary with different transition limit TRN values. Thefixed order power waveforms of FIG. 6A, FIG. 6B, FIG. 6C, and FIG. 6Dhave a power input parameter ISP equal to 19, a total bit resolution RESequal to 5, and an amplitude bit resolution AMP equal to 3. Thetransition limit TRN of FIG. 6A, FIG. 6B, FIG. 6C, and FIG. 6D is equalto 3, 2, 1, and 0, respectively. FIG. 7A, FIG. 7B, FIG. 7C, and FIG. 7Dillustrates how the fixed order power waveforms of FIG. 6A, FIG. 6B,FIG. 6C, and FIG. 6D vary with a different amplitude bit resolution AMPvalue. The amplitude bit resolution AMP of FIG. 7A, FIG. 7B, FIG. 7C,and FIG. 7D is equal to 2.

The optical image stabilization circuit 18 disclosed herein is capableof generating linear power drive signals, standard pulse-widthmodulation power drive signals, and multi-state pulse-width modulationpower drive signals to drive the actuator 14. The frequency of the powerdrive signals are limited only by the speed of the power waveformgenerator 26 and the power waveform conversion circuit 28 of the drivecircuit 24.

It should be understood that, although the drive circuit 24 is discussedin the context of optical image stabilization, the drive circuit 24 maybe applied to any application with an actuator.

The various embodiments described above can be combined to providefurther embodiments. All of the U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet areincorporated herein by reference, in their entirety. Aspects of theembodiments can be modified, if necessary to employ concepts of thevarious patents, applications and publications to provide yet furtherembodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

The invention claimed is:
 1. A system, comprising: a lens located in ahousing; an actuator configured to move the lens; a position sensorconfigured to measure a position of the lens and generate position dataof the measured position of the lens; a gyroscope configured to measuremovement of the housing and generate movement data of the measuredmovement of the housing; a microcontroller configured to determine apower input parameter based on the position data and the movement data;a drive circuit, including: a power waveform generator configured togenerate a power waveform, the power waveform having a first amplitudevalue for a first time duration, a second amplitude value for a secondtime duration, and a third amplitude value for a third time duration,the first, second, and third amplitude values each being determined bythe power input parameter, the power waveform generator configured tocalculate an initial amplitude value of the power waveform, a minimumamplitude value of the power waveform, a maximum amplitude value of thepower waveform, and timings of the minimum and maximum amplitude valuesusing the power input parameter; and a power waveform conversioncircuit, including: a digital to analog converter configured to convertthe power waveform to a voltage signal by converting the first, second,and third amplitude values to first, second, and third voltages,respectively; a voltage to current converter circuit configured toconvert the voltage signal to a current signal, the drive circuit beingcoupled to and configured to drive the actuator with the current signalto move the lens.
 2. The system of claim 1, wherein the digital toanalog converter is configured to dynamically adjust the voltage signalto minimize an offset error.
 3. The system of claim 1, wherein thevoltage to current converter circuit applies a gain to the voltagesignal.
 4. The system of claim 1, wherein the first time duration is thesame length as the second time duration, and the third time interval istwice as long as the second time duration.
 5. The system of claim 1,wherein the power waveform generator is further configured to set thefirst amplitude value to the initial amplitude value, set the secondamplitude value and the third amplitude value to the maximum amplitudevalue or the minimum amplitude value based on the calculated timings ofthe minimum and maximum amplitude values.
 6. A system, comprising: alens located in a housing; an actuator configured to move the lens; aposition sensor configured to measure a position of the lens andgenerate position data of the measured position of the lens; a gyroscopeconfigured to measure movement of the housing and generate movement dataof the measured movement of the housing; a drive circuit, including: apower waveform generator configured to: generate a power waveform basedon the position data and the movement data; and calculate an initialamplitude value of the power waveform, a minimum amplitude value of thepower waveform, a maximum amplitude value of the power waveform, andtimings of the minimum and maximum amplitude values using a power inputparameter; and a power waveform conversion circuit, including: a digitalto analog converter configured to convert the power waveform to avoltage signal; a voltage to current converter circuit configured toconvert the voltage signal to a current signal, the drive circuit beingconfigured to drive the actuator with the current signal to move thelens.
 7. The system of claim 6, wherein the digital to analog converteris configured to dynamically adjust the voltage signal to minimize anoffset error.
 8. The system of claim 6, wherein the voltage to currentconverter circuit applies a gain to the voltage signal.
 9. The system ofclaim 6, wherein the power waveform has a first amplitude value for afirst time duration, a second amplitude value for a second timeduration, and a third amplitude value for a third time duration, thefirst amplitude value being set to the initial amplitude value, thesecond amplitude value and the third amplitude value being set to themaximum amplitude value or the minimum amplitude value based on thecalculated timings of the minimum and maximum amplitude values.
 10. Thesystem of claim 9, wherein the first time duration is the same length asthe second time duration, and the third time interval is twice as longas the second time duration.
 11. A drive circuit, comprising: a powerwaveform generator configured to: receive a power input parameter;generate a power waveform based on the power input parameter; andcalculate an initial amplitude value of the power waveform, a minimumamplitude value of the power waveform, a maximum amplitude value of thepower waveform, and timings of the minimum and maximum amplitude valuesusing the power input parameter; and a power waveform conversioncircuit, including: a digital to analog converter configured to convertthe power waveform to a voltage signal; and a voltage to currentconverter circuit configured to convert the voltage signal to a currentsignal, the drive circuit being configured to drive an actuator with thecurrent signal to move a lens.
 12. The drive circuit of claim 11,wherein the digital to analog converter is configured to dynamicallyadjust the voltage signal to minimize an offset error.
 13. The drivecircuit of claim 11, wherein the voltage to current converter circuitapplies a gain to the voltage signal.
 14. The drive circuit of claim 11,wherein the power waveform has a first amplitude value for a first timeduration, a second amplitude value for a second time duration, and athird amplitude value for a third time duration, the first amplitudevalue being set to the initial amplitude value, the second amplitudevalue and the third amplitude value being set to the maximum amplitudevalue or the minimum amplitude value based on the calculated timings ofthe minimum and maximum amplitude values.
 15. The drive circuit of claim14, wherein the first time duration is the same length as the secondtime duration, and the third time interval is twice as long as thesecond time duration.